Scientists Explore Use of Genetically Engineered Insects

Jul 14, 2017  | 7 min  | Ep4247

Tennessee joined other Southern States in limiting the use of herbicides containing Dicamba. Missouri and Arkansas have already changed policy on the chemical’s application following complaints.

As chemicals are used to fight weeds, it wouldn’t have been possible without a change in genetics. And trait manipulation isn’t just for plants. Genetically engineered bugs are also enlisted in the fight against unwanted guests.

Colleen Bradford Krantz has our Cover Story.

Last summer, some southern Floridians were pondering the possible release of a transgenic mosquito that might slow the spread of the Zika virus. Sam Glucksman, a plant doctor at Hundley Farms, was less concerned about a genetically modified bug than the cornsilk flies invading the company’s sweetcorn fields.

Sam Glucksman, Hundley Farms, Loxahatchee, Florida: “Not many people are talking about it. Again, it probably has a lot more to do with the fact that we don’t have a lot of Zika cases in Palm Beach County – or at least where I am. I would say down south they are probably talking about it a lot more.”

Residents of the Florida Keys, where release of the newly engineered bug is still pending, did talk about it; some protesting and others advocating for slowing the spread of the potentially debilitating virus.

The genetically engineered mosquito joins an altered diamondback moth in New York state in having the federal government’s green light in terms of “no significant environmental impact” related to pending open-field trials

Several decades of lab work have set in motion the potential for genetically altered bugs that some say may reduce the use of pesticides while protecting human health. The mosquito species that carries malaria in Africa is anticipated to be an early target.

David O’Brochta, Institute for Bioscience and Biotechnology Research, University of Maryland: “In the case of insects of human health concern, there’s a strong argument to be made that eliminating those insects locally or perhaps even globally might actually be a good thing.”

Some, however, are leery of being quite so aggressive in altering a species’ population.

David O’Brochta, Institute for Bioscience and Biotechnology Research, University of Maryland: “These mosquitoes have a role in the ecosystems in which they live. In the case of Anopheles gambiae in Africa, this is their natural environment …We are not talking about wiping out all 3,000 species of mosquitoes that exist in the world. It’s a technology that would be specifically targeted in the case of Africa to the human malaria-transmitting mosquito, Anopheles gambiae.”

Regardless, O’Brochta and Glucksman believe the public needs to be better informed.

Sam Glucksman, Hundley Farms, Loxahatchee, Florida: “Most average people really don’t know the facts and science behind it… I think the biggest misconceptions are these animals are going to somehow get loose and mate with another native indigenous species and somehow create some crazy mutant that’s going to be resistant to everything and is going to eat your children while you sleep. People are just so scared. And they don’t need to be so scared.”

The engineered mosquitos, developed by the Britain-based company Oxitec, contain a self-destruct mechanism created by inserting a gene into the bugs’ DNA. The gene causes the mosquito’s offspring to die before reaching adulthood.

Other nations have released Oxitec’s mosquitos in early tests aimed at reducing illness and death from mosquito-borne disease.

Besides potentially benefitting human health, proponents also see the possibility of using genetically engineered bugs to reduce insecticide use.

Sam Glucksman, Hundley Farms, Loxahatchee, Florida: “If it works, great. Then we don’t have to introduce possible poisons or toxins to the environment and kill off non-target animals. That would be the pro. The con would be… what’s saying that those mosquitos are going to stay here? It’s just like any other biological control: you can release them, but as soon as you do, they are free to go wherever they want. It doesn’t mean they are going to stay here and take care of your problem. They might go next door and take care of that guy’s problem.”

As with the decades-old radiation sterilization programs that nearly wiped out problematic insects, entomologists like O’Brochta the releases would need to be coordinated over a large geographic area.

Oxitec also is involved with Cornell University’s pending field trials in upstate New York, where genetically engineered diamondback moths would be released in a 10-acre area. Female offspring die before reproducing. Diamondback moths, which quickly develop resistance to insecticides, cause an estimated $4 billion in damage worldwide annually to food crops like broccoli, cabbage and cauliflower.

Sam Glucksman, Hundley Farms, Loxahatchee, Florida: “In the plant crop world, it’s a huge catch 22 because people complain that we use too many chemicals. But yet you don’t want a single spot on your tomato and you want that tomato to be nice and juicy. But you don’t want any bruises on it. It can’t have any pesticides on it whatsoever. It has to be totally clean and perfect and the right color. It can’t be kind of green. It has to be all red. …You know, at the same time, the only way to do that is to use the very thing you are telling us not to use.”

O’Brochta says that gene drive –a more powerful tool that has yet to be tested outside the laboratory – allows an individual bug’s entire genetic code to be passed to nearly all of its offspring. By engineering all the insects to be male, for example, scientists could wipe out a species in an area. Gene drive, which can occasionally occur in nature, could help reduce human health threats or push out invasive species from an area. Non-native insects and pathogens cost an estimated $40 billion annually in the United States alone. This is not to say that the scientific community has not considered the pitfalls to the process.

David O’Brochta, Institute for Bioscience and Biotechnology Research, University of Maryland: “There’s been a lot of discussion about applying these types of technologies for the purposes of controlling, say, invasive species of all types, not just insects, but fish and plants and so on. … The environmental impact can’t be dismissed. And needs to be investigated for each of these situations where people are planning to try to eradicate a species from an environment.”

According to O’Brochta, those who research gene drive’s potential also are looking for a way to “turn off” any modifications should something go wrong. They will also consider potential impact on other species should one disappear.

Companies like Oxitec have been waiting for federal or local approval before releasing their genetically altered bugs. It remains to be seen how the rest of the country will view the potential risks and rewards of this new approach for battling pests.

For Market to Market, I’m Colleen Bradford Krantz.

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